JP2000068890A - Transponder system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transponder system where a transponder transmits data with security to an inquiry device even at a remote distance without receiving interruption from other transmitter. SOLUTION: The transponder system is provided with an inquiry device 12 and a transponder 14 and when the transponder 14 receives inquiry data in a form of a pulse width modulation carrier sent from the inquiry device 12, the transponder modulates the received carrier with an FSK signal and transmits resulting reply data. The FSK frequency is generated by applying frequency division to the carrier received by the transponder 14 and its range is set so that the carrier of the existing transmitter is not placed therein. Two FSK frequencies are selected within the range and not interfered with the existing transmission frequency and to be obtained by an even number division ratio from the carrier frequency. A baud rate of data transmission is set to be obtainable by an integer division number ratio from the carrier frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a transponder device including an inquiry device and a transponder. After receiving the inquiry data sent from the inquiry device, the transponder transmits response data after confirming that the inquiry data is inquiry data addressed to itself.

[0002]

2. Description of the Related Art A transponder device of this kind is disclosed, for example, in European Patent Publication No. 301 127 B1. In this known transponder device, the interrogator sends an interrogation signal in the form of a radio frequency pulse having a predetermined duration to the transponder. The transponder receives the radio frequency pulse, rectifies it, and charges the storage capacitor. At the end of the radio frequency pulse, a sufficient level of voltage is stored on the capacitor. This capacitor is used as a power source for an electronic circuit in the transponder. The electronic circuit transmits the identification code stored in the transponder. Thus, the query device knows that the transponder having the received identification code is within its transmission range.

[0003] Conventional transponder devices can only use limited energy to send back the identification code. This is because the size of the storage capacitor is limited because the transponder is small. Due to the small amount of energy available, the range of signals transmitted by the transponder is also limited.

[0004] European Patent Publication 0 473 569 A
Discloses a transponder device that uses ASK modulation to transmit data from the transponder to an interrogation device. To transmit the data values "0" and "1" of a digital signal with this type of modulation, a carrier signal of each amplitude assigned to the data value is emitted. This type of transmission is susceptible to interference. This is because an interference source is usually present in the surroundings and affects the amplitude of the signal, so that the interpretation of the signal always involves an error. This type of modulation is particularly unsuitable for mobile transponders. Because the transponder moves, the amplitude of the transmitted signal fluctuates,
This is because it causes a misinterpretation of the signal.

[0005] European Patent Publication 0 258 415 B
Uses Manchester encoding for data transmission between itself and the interrogator. In this type of encoding, a signal having a data value "0" is represented by providing a large pause between the pulses sending the data value "1". This type of encoding is based on the transmitted R
It is not suitable for a passive transponder which is a method of obtaining power from the F signal. Manchester encoding uses long pauses, resulting in insufficient power over a wide range of signals sent back from the transponder. Furthermore, the conventional transponder device described in this patent operates in the low frequency range, which requires large components (eg, large capacitors and inductances) that operate slowly.

[0006]

SUMMARY OF THE INVENTION The present invention provides a transponder device capable of transmitting data safely from a transponder to an inquiry device even at a long distance without being substantially affected by interference. Since this device can be manufactured inexpensively, this transponder can be mass-produced and used for many applications.

According to the present invention, this object can be achieved by a transponder device having the following functions. a) the interrogator transmits the interrogation data in the form of a pulse width modulated carrier; b) the transponder modulates the received carrier with an FSK signal and retransmits the response data as an FSK signal to the interrogator; c) The generation of the FSK frequency is performed by frequency division of the carrier received by the transponder; d) The range of the FSK frequency is set so that the carrier of the known transmitter does not fall within this range; e) Two FSKs Set the frequencies within this range so that they are not interfered with by the known transmission frequency at their baseband; f) set the two FSK frequencies within this range to be obtained from the carrier frequency by an even division ratio; g The baud rate for data transmission from the interrogator to the transponder and from the transponder to the interrogator is the carrier frequency. Is set so as to be obtained by an integer division ratio.

[0008] The transponder device of the present invention is optimized to allow for fault-free data transmission between the transponder and the interrogation device at all points. Combining the functions shown here, the interrogator receives weak signals transmitted from the transponder with high probability. This is because the relevant frequency is selected without collision with the known transmission frequency. Further, by selecting and combining various functions, a transponder can be realized with minimum hardware, and the object of using the transponder as a mass-produced product can be achieved.

[0009] Further developments of the invention are set out in the dependent claims. The present invention will be described in detail below using an example to which the combination of functions of the present invention can be applied, with reference to drawings showing a transponder device.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION

DESCRIPTION OF THE PREFERRED EMBODIMENTS The main part of the transponder device 10 is an inquiry device 12 which can exchange data with at least one transponder 14. To initiate a data exchange, interrogator 12 transmits interrogation data 18 to transponder 14 through its antenna 16.
Transponder 14 receives this interrogation data via its antenna 20. In response to the query data, the transponder transmits a response carrier frequency within the ISM frequency range. ISM is an acronym for "Engineering, Science and Medicine" and refers to the range in which engineering, scientific and medical equipment operates.

The carrier generated by the RF oscillator 24 is modulated by a modulator 26 to represent data. This data is, for example, an address stored in the transponder 14. Using this address, the transponder 14 can be addressed by a predetermined method and its identification code can be transmitted. This identification code may be the same as the address.
The modulated carrier is sent to antenna 16 and radiated from this antenna. The modulator performs pulse width modulation. This will be briefly described with reference to FIG. 4A. The upper part of FIG. 4A represents the digital bits of the interrogation signal to be transmitted.
The lower part shows the RF carrier modulated by these bits. As can be seen, each digital bit begins with a short pause of duration τ. This idle period has a logic initialization function, after which the digital bit is set to 2 bits.
If it has a binary value "1", the RF pulse of the duration T1
If the digital bit has a binary value "0", an RF pulse of duration T2 follows.

FIG. 4B illustrates that this type of pulse width modulation is suitable for long-distance transmission between an interrogator and a transponder. This description considers that for transmission of RF signals in different frequency ranges, the standards for each transmission field strength apply to avoid mutual interference between transmitters operating in adjacent areas. The transponder device described here operates at a carrier frequency of 13.56 MHz and is subject to FCC standards 15.225 and 15.20.
9 applies. In a coordinate system with frequency on the horizontal axis and field strength on the vertical axis, these two standards have a template T that is the upper threshold for each field strength at each frequency.
These standards specify 13.553 MHz and 13.567.
The electric field strength generated by the carrier frequency between 30 MHz is 30 m
Should not exceed 10,000 μV / m. Outside this range, the electric field strength should not exceed 30 μV / m.

In the case of digital data transmission using Manchester encoding, for example, an IEEE communication magazine (I
EEE Communications Magazine), Dec. 1984, vol. 2
As described in 2, no. 12, p. 23, at a distance of 30 m, the carrier reaching almost the limit electric field strength of 10,000 μV / m has a modulation spectrum S _MC exceeding the limit specified in the standard. (1) is generated. This range is shown in FIG.
This is indicated by the shaded portion of B. The electric field intensity is the spectrum S of FIG. 4C.
This limit value can be maintained only when the carrier power is reduced to such an extent that the allowable limit value indicated by _MC (2) is not exceeded. This, of course, means operating with reduced transmitter range and reduced carrier power.

The pulse width modulation used by the transponder device described herein has a duration τ between successive RF pulses.
The modulation spectrum does not exceed the limit specified in the above standard even when the electric field strength generated by the carrier power approaches the upper limit of 10,000 μV / m. S _PWM The spectrum in FIG. 4B
Indicated by This is in fact the transmission between the transponder and the interrogator, which must be greater than for devices using Manchester coding, since the transmission takes place at a higher carrier power, while still adhering to the limits specified in the standard. Means you can do it. Since the duration τ of the pause between RF pulses is shorter than the duration of the pulse, energy is efficiently transmitted to the transponder. Thus, the transponder can receive enough energy to process the received data and retransmit the stored data.

Next, FIG. 3 shows a block diagram of a transponder, which will be described. That is, the effect on the transponder 14 when receiving the inquiry signal transmitted from the inquiry device 12 will be described. Transponder 14 receives an interrogation signal in the form of a sequence of radio frequency pulses at antenna 20 and rectifies it at rectifier circuit 30.
The rectified voltage is buffered and becomes the supply voltage for all electronic circuits in transponder 14. Since the pulse interval τ shown in FIG. 4A is shorter than the duration of the radio frequency pulse, a voltage sufficient to supply the electronic circuit is always obtained.

The received inquiry signal is demodulated by the demodulator 32. Demodulator 32 may be a conventional pulse width modulated signal demodulator. The demodulator shown in FIG. 5A has a signal converter 500 as an input stage, converts the amplitude-modulated RF signal received by the antenna using, for example, a diode, and has a different duration with a single polarity and a continuous duration. Generate a series of pulses with a pause of time τ. The signal leaving signal converter 500 has a high voltage value "H" when a pulse of duration T1 or T2 is present, and has a low voltage value L during a pulse pause of duration τ. The output signal of the signal converter 500 is shown in FIG. 5B. It should be noted here that the information contained in this signal exists not in the form of pulse amplitude but in the form of individual durations, and that the long duration T
1 means the data value "1", and the short duration T2 means the data value "0".

In the demodulator shown in FIG. 5A, the signal converter 50
The signal exiting zero enters input 510 of AND gate 512. The other input of AND gate 512 has a data value of “1”.
Is always received with a signal having a high voltage value "H" corresponding to.
The output of AND gate 512 connects to the start input 514 of counter 516. Counter 516 also has a clock input 518 and a cancellation input 520. The counter 516 receives the start signal on the start input 514, and
Start counting the clock signals provided to. Counter 516 has two outputs 522 and 524. When the time interval T2 elapses, an output signal having a data value “1” appears at the output 522, and when the time interval T1 elapses, a signal having the data value “1” appears at both the outputs 522 and 524.

For example, when a signal having a data value "1" is applied to the cancel input 520 through a delay circuit 526 comprising four NOT gates, the count value of the counter 516 is erased. The outputs 522 and 524 of the counter 516 connect to the inputs of an AND gate 528, and the output of the AND gate 528 connects to the input of the intermediate memory. Intermediate memory 34 receives an acceptance signal at its acceptance input 532,
The signal value supplied from the D gate 528 is received and stored. The acceptance signal is supplied from the output of the NOT gate 534. The output of NOT gate 534 is also connected to the input of delay circuit 526, whose input is connected to input 510. The data received by the antenna in the form of an RF signal exits the output of the intermediate memory 34 as demodulated binary data.

Next, a method for demodulating the RF pulse sequence shown in FIG. 4A by the demodulator of FIG. 5A when the RF pulse sequence is present will be described.

As mentioned above, the signal converter 500 generates from the amplitude modulated RF signal a signal formed of rectangular pulses of different duration with a pulse pause τ in between.

The first pulse emanating from signal converter 500 is a pulse having a long duration T1 and, when its high voltage value "H" is applied to AND gate 512, its second pulse.
Since the input always has a high voltage value, the AND gate 512 outputs a high value "H", which is the start input 51.
At 4, the counter 516 begins counting the clock signal provided to the clock input 518. At the end of the pulse (ie at the end of the duration T1), the counter outputs 5
The capacity of counter 516 and the frequency of the clock signal are selected so as to reach a count that yields a high value from both 22 and output 524. As a result, the output of the AND gate 528 also outputs a signal having a high value, which is applied to the input of the intermediate memory 34.

At the same time as the end of the pulse of the duration T1, the pulse pause of the duration τ starts, and a signal having a low voltage value L is present at the input 510, and is inverted by the NOT gate 534 to change the high voltage value “H”. Is converted into a signal having This signal enters the accept input 532 of the intermediate memory 34, which accepts and stores the high voltage value at that input representing the data value "1". At the same time, after a signal having a high voltage value comes out of the output of the NOT gate 534 and is delayed by the delay circuit 526, the cancellation input 520 of the counter 516 is output.
Then, the count of the counter 516 is reset to zero.
Now, the intermediate memory 34 contains the data value “1” corresponding to the first RF pulse. To store a plurality of data values of a data word in this intermediate memory 34, it is best if the intermediate memory is a shift register. The shift register advances the contents of its data by one stage each time it receives an accept signal at its accept input 523, while further adding an AND gate 528
Accepts the next data value given to that input from.

Receiving the data signal shown in FIG. 4A means that after a time interval τ has elapsed (ie, two RFs).
(After a pause between pulses) to receive an RF pulse of short duration T2. Receiving this pulse also causes a new operation of counter 516 and counter 516
Starts counting clock pulses again. At the end of time interval T2, counter 516 reaches a count that provides a signal having a high value "1" at output 522 only and a signal having a low value "0" at output 524. As a result, AND gate 5
From the output of 28, a signal having a low value "0" is output and enters the input of the intermediate memory 34. When a pulse pause of the next duration τ starts, a signal having a high value “H” is again supplied from the NOT gate 534 to the reception input 532 of the intermediate memory 34, and the data corresponding to the low value L of the output of the AND gate 528. The value “0” is stored in the intermediate memory 34.

As mentioned above, all RF pulses of the received RF data signal are converted to data values "1" or "0" according to their duration, and each time an acceptance signal is received at input 532, intermediate memory 34 is received. Is stored. Thus, in each case, the acceptance signal is generated at the beginning of the pause between two RF pulses.

When the demodulation of all data values is completed, the demodulated data is prepared in the intermediate memory 34, and this is compared with the data stored in the address memory 38 by the comparator 3.
Compare within 6.

The signal received by the antenna 20 also enters the frequency divider 40. The frequency divider 40 outputs a switching signal to three outputs, as described below. Each of these frequencies is obtained from the carrier frequency of the interrogation signal by an integer division ratio. Further, since the carrier of the inquiry data is continuously transmitted, the resonance circuit 42 tuned to the carrier causes resonance.

If it is determined that the data in the intermediate memory 34 and the data in the address memory 38 are the same, a switch signal is output to the output 44 of the comparator 36 and the switch 46 is closed. When the switch 46 is closed, the address memory 38
Is transferred to the shift register 48. At the same time, the switch 50 is closed by the switching signal from the output 44 of the comparator 36, and the clock signal is supplied to the shift register 48 from the output 52 of the frequency divider 40. At the frequency of this clock signal, data is transferred from the shift register to the two-way switch 54. When the data value from the shift register 48 is a binary value "1", the switch 54 connects the output 56 of the frequency divider 40 to the switching input of the switch 58, and the data value from the shift register 48 becomes the binary value " In the case of "0", the switch 54 connects the output 60 of the frequency divider 40 to the switch 58.

As described above, the output 56 of the frequency divider 40
And 60 have different frequencies, which correspond to the data values "0" and "1" of the information to be transmitted. The signals from the outputs 56 and 60 of the frequency divider 40 are sent to a switch 58 according to the setting of the two-way switch 54.
The switch 58 is designed to open and close according to each frequency supplied from the frequency divider. Now, it is assumed that a signal having a data value “0” is output from the output of the shift register 48. In the case of this signal, the output 6 of the frequency divider 40
The two-way switch 54 is set such that 0 is connected to the operation output of the switch 58. Thus, in this case, the switch 58 opens and closes according to the frequency of the signal at the output 60 of the frequency divider 40.

As can be seen, when switch 58 is closed, resistor 62 is connected in parallel with resonant circuit 42 in the circuit. Therefore, the resonance circuit 42 attenuates the vibration each time the switch is closed. Since the fundamental oscillation of the resonance circuit 42 follows the amplitude modulation, the spectrum of the signal obtained from the resonance circuit 42 as a result of the attenuation of the oscillation becomes the resonance circuit 4 forming the carrier frequency.
2 and the carrier frequency and the frequency divider 4
It consists of two sidebands corresponding to the sum and difference of the frequency of the output 60 of 0 (the switch 58 opens and closes at this frequency).

When the shift register 48 outputs a signal with a data value "1" at its output, the two-way switch 54 operates to connect the output 56 of the frequency divider 40 to the input of the switch 58, and the switch 58 operates at the output 56. It opens and closes at the frequency that comes out. Also in this case, the resonance circuit 42 attenuates the vibration by the resistor 62 according to the switching frequency of the switch 58,
The amplitude modulation of the carrier wave formed by the fundamental vibration of the resonance circuit 42 is performed. Therefore, the output spectrum of the resonance circuit 42 is composed of the carrier frequency and two sidebands corresponding to the sum and difference of the carrier frequency and the frequency output from the output 56 of the frequency divider 40.

Accordingly, the spectrum of the signal transmitted from the antenna 20 has a carrier frequency corresponding to the fundamental frequency of the resonance circuit 42 and two sidebands, that is, the shift register 48 has one data value (in the above example, one data value). When the signal having the data value “0” is output, the signal resulting from the amplitude modulation performed by the frequency from the output 60 of the frequency divider 40 and the shift register 48 output another signal (in the above example, the data value “1”). ) At the output of the frequency divider 40, resulting from amplitude modulation performed by the frequency from the output 56 of the frequency divider 40. Therefore, the transmission of information using the method described herein involves transmitting data values of a binary signal on a first frequency and a second frequency.
The transmission is based on the principle.

The baud rate of information transmission (ie, the frequency at which individual data values are generated one after another) is determined by the frequency at which the shift register 48 outputs individual data values.
As can be seen from FIG. 3 and as previously described, a data value is output in response to a signal coming out of output 52 of frequency divider 40 and being provided to shift register 48 via switch 50.

[0033] The interrogation device uses the antenna 16 for FSK.
Receives the modulated carrier and sends it to switch 64. The switch 64 disconnects the reception unit of the inquiry device from the transmission unit during transmission of the inquiry data. The opening and closing of the switch is controlled by the sequence control processor 66. The processor 66 supplies the corresponding switching signal a to the switch 64 as soon as the transmission of the inquiry data is completed.

The receiving section of the inquiry device 12 comprises a conventional diode mixer 68. Diode mixer 68 demodulates the FSK modulated carrier in a known manner and provides at its output two FSK frequencies at baseband. When the output signal of the diode mixer 68 is amplified by the amplifier 70 and filtered again by the low-pass filter 72, the signal has no carrier frequency. This signal is transmitted to the FSK by the two-way switch 74.
It is provided to a demodulator 76. The data transmitted from transponder 14 is demodulated and exits at the output of demodulator 76.

However, due to interference, it is not always possible to satisfactorily demodulate received data in this way. Therefore, in order to enhance the security of data transmission from the transponder to the inquiry device, the receiving unit of the inquiry device is devised to perform another demodulation. That is, FS
The data demodulated by the K demodulator 76 is sent to a check device 78 to check whether the data is complete. Knowing what kind of data will be returned from the transponder, the checking device can determine whether this data makes sense (ie, whether it is highly likely that it is not erroneous data)
Or check if data is corrupted due to interference. In the latter case, when the check device 78 sends a signal to the operation control processor 66, the processor 66 gives the two-way switch 74 a switching signal b. This switching signal b is 2
Reset direction switch 74 to provide the signal coming from low pass filter 72 to ASK demodulator 80.

The demodulator 80 performs ASK demodulation on the signal, and identifies the binary value contained in the signal not by its frequency but by its amplitude. Since the two frequencies in the output signal of the diode mixer 68 have different values, when filtered by the low-pass filter 72, the two signal components having different frequencies have different amplitudes. Therefore, it is possible to demodulate not only for two frequencies but also for two amplitudes. In addition, the output signal of ASK demodulator 80 is also provided to checking device 78, which checks the integrity of the demodulated data. When the checking device 78 confirms that the data is significant, the data from the ASK demodulator is further processed as data transmitted from the transponder 14.

Upon detecting that the received data is defective, the checking device 78 also sends a control signal to the operation control processor 66. When the processor 66 provides the switch 84 with the switching signal c, the switch 84 is closed and
The signal received by the antenna 16 and transmitted through the transmission / reception switch 28 is supplied to the filter 86, and the upper band is filtered out of the spectrum of the received signal as shown in FIG. Filter 8
6 is converted to an intermediate frequency range in a mixer which also receives the output frequency of the first local oscillator 90, and the converted signal is supplied to an FSK demodulator 94 via a two-way switch 92. The FSK demodulator 94 recovers transmission data by FSK demodulation. As before, the checking device 78 checks the integrity of the demodulated data.

If the data generated by the FSK demodulator is defective, the checking device 78 also sends a control signal to the operation control processor 66. The processor 66 supplies the switching signal d to the two-way switch 92, and converts the intermediate frequency signal supplied from the mixer 88 to the ASK demodulator 9 instead of the FSK demodulation.
6 performs ASK demodulation.

If the tick device 78 again detects that the signal from the ASK demodulator 96 is defective, it provides a control signal to the operation control processor 66. When processor 66 provides switch signal e to switch 98, switch 98 closes and provides the signal received at antenna 16 to filter 100 to filter out the lower sideband from the received signal. As in the previous process, the filtered signal is converted to an intermediate frequency range by mixer 102, which also receives the output frequency of local oscillator 104. The converted IF signal is subjected to FSK demodulation or ASK demodulation in some cases as before.

The signal processing is performed in the receiving section of the inquiry device 12 in this manner, and since the transmission data is obtained from the received signal using a plurality of methods, it can be seen that the reliability is high. With this method, the interrogator can receive and evaluate a signal transmitted with very low power from the transponder with high probability even under bad reception conditions.

In one application, the carrier of the signal transmitted from the interrogator is set at 13.56 MHz. The two frequencies representing the data value “1” and the data value “0” are 48
Set to 4.2 kHz and 423.75 kHz, respectively. The reason for this is that these frequencies can be used to prevent the sidebands generated during modulation from colliding with strong transmitters that are known to be present. In addition, using these two frequency values, the interrogator does not collide with the known intermediate or long wave transmitter after conversion to baseband, so the interrogator does not need to know what the transponder is transmitting at very low power. This can be handled without any problems.

With respect to the choice of the two frequencies, there is another advantage that they can be obtained from the carrier frequency by an integer division ratio. The higher frequency 484.28 kHz is a value obtained by dividing the carrier frequency 13.56 MHz by 28, and the lower frequency 423.74 kHz is a value obtained by dividing the carrier frequency by 32.
Divided by.

In order that the spectrum created by the interrogator based on the baud rate of the transmitted signal does not interfere with the signal sent back from the transponder as much as possible,
The baud rate is selected so that one FSK frequency is near the zero of the spectrum. This baud rate setting is
Time intervals τ, T1, T2 of signals transmitted by the inquiry device
Affected by the corresponding setting.

It should be noted that the transponder device described herein does not depend on the specific structure of the individual components illustrated. The most important point in achieving a given data security in an economical design is rather the selection of appropriate system parameters. This is defined in the claims.

With respect to the above description, the following items are further disclosed. (1) The transponder 14 includes the query device 12 and the transponder 14. After receiving the query data transmitted from the query device 12, the transponder 14 confirms that the query data is the query data addressed to itself. A transponder device for transmitting response data, wherein: a) interrogator 12 transmits interrogation data in the form of a duration modulated carrier within a narrow predetermined frequency range; b) transponder 14 transmits said received carrier to an FSK signal. And retransmit the response data as an FSK signal to the interrogation device 12; c) generating the FSK frequency by the transponder 14
Performs the frequency division of the received carrier, d) sets the range of the FSK frequency so that the carrier of the known transmitter does not fall within this range, and e) sets the two FSK frequencies into this range. Within the baseband so as not to interfere with the known transmission frequency; f) the two FSK frequencies are set within this range from the carrier frequency at an even division ratio; g) the query device A transponder device, wherein the baud rate of data transmission from 12 to the transponder 14 and from the transponder 14 to the inquiry device 12 is set so as to be obtained from the carrier frequency by an integer division ratio.

(2) The transponder device according to item 1, wherein the inquiry data is transmitted in the form of binary encoded data, and one of the binary values is transmitted by a radio frequency pulse having a first duration. Transmitted, the other binary value being transmitted by a radio frequency pulse of a second duration, with a pulse pause before each radio frequency pulse, the duration of which is said first duration.
And a transponder device shorter than the second duration. (3) The transponder device according to (2),
The baud rate of the transmission of the inquiry data is determined by the two FSKs in the transmission spectrum generated by the inquiry device 12.
A transponder device that sets the frequency near the zero point.

(4) The transponder device according to any one of the above items, wherein the interrogation device includes a receiving unit, and the receiving unit can switch to a different type of modulation according to the integrity of the received data. , Transponder device. (5) The transponder device according to item 4, wherein
A transponder device capable of converting the received data into baseband by a diode mixer in a receiving unit of the inquiry device 12 and performing FSK or ASK modulation in the baseband.

(6) The transponder device according to item 4, wherein the reception data can be obtained by demodulating an upper sideband or a lower sideband of a reception spectrum in a reception unit of the inquiry device 12. Transponder device. (7) The transponder device according to any of the above items, wherein the narrow predetermined frequency range is an ISM range.

(8) The transponder device includes an inquiry device 12 and a transponder 14. After receiving the inquiry data transmitted from the inquiry device 12, the transponder 14 sends the inquiry data to the own device. After confirming that the data is the matching data, the response data is transmitted. The interrogator 12 transmits the interrogation data in the form of a pulse width modulated carrier within the ISM frequency range. The transponder 14 modulates the received carrier with an FSK signal,
The response data is sent back to the inquiry device 12 in the form of an FSK signal. The generation of the FSK frequency is performed by the transponder 14.
Is performed by frequency-dividing the received carrier. The range of the FSK frequency is set so that the carrier of the known transmitter does not fall within this range. Two FSKs
The frequency is set so as not to interfere with a known transmission frequency in the baseband within this range, and to be obtained from the carrier frequency in an integer division ratio. The baud rate of data transmission from the interrogator 12 to the transponder 14 and from the transponder 14 to the interrogator 12 is set so as to be obtained from the carrier frequency in an integer division ratio.

[Brief description of the drawings]

FIG. 1 is a basic structure of a transponder device.

FIG. 2 is a block circuit diagram of an inquiry device used for describing the device of the present invention.

FIG. 3 is a block circuit diagram of a transponder used for describing the device of the present invention.

FIG. 4A is a diagram illustrating pulse width modulation of a data signal transmitted from a query device to a transponder. B and C are diagrams showing a frequency spectrum of a frequency modulation signal.

FIG. 5A is a circuit diagram showing an example of a demodulator suitable for the transponder device of the present invention. FIG. 5B is a diagram showing an output signal of a signal converter used in the demodulator of FIG. 5A.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Transponder device 12 Inquiry device 14 Transponder 16 Inquiry device antenna 20 Transponder antenna

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kostas Aslanideis, Germany Mohsburg, Ampere-Wuerrestraße 20 (72) Inventor Andreas Haglu, Dachau, Germany 6

Claims (1)

[Claims] An inquiring device (12) and a transponder (14) are provided, and after receiving the inquiring data transmitted from the inquiring device (12), the transponder (14) transmits the inquiring data to its own. A transponder device for transmitting response data after confirming that it is inquiry data, comprising: a) an inquiry device (12) for transmitting inquiry data in the form of a continuous-time modulated carrier within a narrow predetermined frequency range; B) the transponder (14) converts the received carrier to FS
Modulate with the K signal and retransmit the response data as an FSK signal to the interrogator (12); c) The generation of the FSK frequency is performed by transponder (1
4) performing the frequency division of the received carrier; d) setting the range of the FSK frequency so that the carrier of the known transmitter does not fall within this range; e) setting the two FSK frequencies to: Within this range, set so as not to interfere with the known transmission frequency at its baseband; f) Set the two FSK frequencies to be obtained from the carrier frequency at an even division ratio within this range; g) From the matching device (12), the transponder (1
The transponder device according to claim 4, wherein the baud rate of data transmission from the transponder (14) to the inquiry device (12) is set so as to be obtained from the carrier frequency by an integer division ratio.